Manifold Pressure/Vacuum Sensor: Description and Operation

Manifold Absolute Pressure (MAP) Sensor, Intake (turbocharged Engines Only, 2002-2004)







The manifold absolute pressure (MAP) sensor detects the pressure in the intake manifold downstream of the charge air cooler (CAC). The signal from the sensor is primarily used by the engine control module (ECM) to check that the correct boost pressure is reached. The boost pressure is governed by the turbocharger (TC) control valve.

The sensor, which is a piezo resistor, is grounded in the control module and supplied with 5 V from the control module.

The resistance in the sensor changes depending on the pressure in the intake manifold, giving a signal of 0 - 5 V. Low pressure results in low voltage, high pressure in high voltage.

The engine control module (ECM) can diagnose the manifold absolute pressure (MAP) sensor. The signal can be read using VADIS.

The manifold absolute pressure (MAP) sensor is in the intake hose for the throttle body (TB).


Manifold Absolute Pressure (MAP) Sensor, Intake (turbocharged Engines Only, 2005-)







The manifold absolute pressure (MAP) sensor detects the pressure in the intake manifold downstream of the charge air cooler (CAC). On 6 cylinder turbocharged engines and B5254T2/-T4, the temperature of the intake air is also detected.

Pressure sensor
The signal from the sensor is primarily used by the engine control module (ECM) to check that the correct boost pressure is reached. The boost pressure is governed by the turbocharger (TC) control valve.

The sensor, which is a piezo resistor, is grounded in the control module and supplied with 5 V from the control module.

The resistance in the sensor changes depending on the pressure in the intake manifold, giving a signal of 0 - 5 V. Low pressure results in low voltage, high pressure in high voltage.

Intake temperature
The temperature sensor detects the temperature of the intake air after the charge air cooler (CAC). This data is used by the engine control module (ECM) to calculate the boost pressure control (turbocharger (TC) and to calculate the injection period. The control module also controls certain diagnostic functions using the signal from the temperature sensor.

The sensor, which is an NTC resistor, is grounded in the control module and supplied with power (signal) from the control module.

The resistance in the sensor changes according to the temperature of the intake air. This provides the control module with a signal of between 0 - 5 V. The lower the temperature the higher the voltage (high resistance). A high temperature results in low voltage (low resistance).

The engine control module (ECM) can diagnose the manifold absolute pressure (MAP) sensor. The signal can be read using VADIS.

The manifold absolute pressure (MAP) sensor is in the intake hose for the throttle body (TB).